The con­clu­sion to Cialdini’s book points out why, in this increas­ingly com­plex world, res­ist­ing attempts at “enforced com­pli­ance” (decep­tion) through these key prin­ciples is as import­ant as recog­nising and respond­ing to truth­ful instances of their imple­ment­a­tion:

Because tech­no­logy can evolve much faster than we can, our nat­ur­al capa­city to pro­cess inform­a­tion is likely to be increas­ingly inad­equate to handle the sur­feit of change, choice, and chal­lenge that is char­ac­ter­ist­ic of mod­ern life. More and more fre­quently, we will find ourselves in the pos­i­tion of the lower animalsâ€”with a men­tal appar­at­us that is unequipped to deal thor­oughly with the intric­acy and rich­ness of the out­side envir­on­ment. Unlike the anim­als, whose cog­nit­ive powers have always been rel­at­ively defi­cient, we have cre­ated our own defi­ciency by con­struct­ing a rad­ic­ally more com­plex world. But the con­sequence of our new defi­ciency is the same as that of the anim­als’ long-stand­ing one. When mak­ing a decision, we will less fre­quently enjoy the lux­ury of a fully con­sidered ana­lys­is of the total situ­ation but will revert increas­ingly to a focus on a single, usu­ally reli­able fea­ture of it.

When those single fea­tures are truly reli­able, there is noth­ing inher­ently wrong with the short­cut approach of nar­rowed atten­tion and auto­mat­ic response to a par­tic­u­lar piece of inform­a­tion. The prob­lem comes when some­thing causes the nor­mally trust­worthy cues to coun­sel us poorly, to lead us to erro­neous actions and wrong­headed decisions.

One con­stant that con­nects us all in some way is that–at the end of our day–we lie down and slowly slip into a state of reduced or absent con­scious­ness and become at the mercy of our fel­low man. Every day we fall asleep: we have done so for mil­lions of years and will con­tin­ue to do so.

Itâ€™s an inter­est­ing quirk of Moth­er Nature â€” that she insists on tak­ing us down to the ground like that, every day, no mat­ter who we are. For all of us, the act of leav­ing con­scious­ness is the same, itâ€™s just our set­tings and situ­ations â€” which bookend that uncon­scious­ness â€” where we dif­fer.

From bone strength and oxy­gen absorp­tion in lar­ger anim­als, to the per­ils of sur­face ten­sion and poor eye design in smal­ler ones: just some ideas to con­sider when study­ing com­par­at­ive ana­tomyÂ andÂ why anim­als are the way they are.

A per­fect take on the top­ic isÂ J. B. S. Haldane’s 1928 On Being the Right Size. In this absorb­ing short essay, Haldane looks atÂ why rhi­nos have short, thick legs; why theÂ smal­lest mam­mal in Spitzber­gen is the fox; and, primar­ily, how the size of an anim­al determ­ines almost everything about its ana­tomy.

There is a force which is as for­mid­able to an insect as grav­it­a­tion to a mam­mal. This is sur­face ten­sion. A man com­ing out of a bath car­ries with him a film of water of about one-fiftieth of an inch in thick­ness. This weighs roughly a pound. A wet mouse has to carry about its own weight of water. A wet fly has to lift many times its own weight and, as every­one knows, a fly once wet­ted by water or any oth­er liquid is in a very ser­i­ous pos­i­tion indeed. An insect going for a drink is in as great danger as a man lean­ing out over a pre­cip­ice in search of food. If it once falls into the grip of the sur­face ten­sion of the waterâ€”that is to say, gets wetâ€”it is likely to remain so until it drowns. [â€¦]

The high­er anim­als are not lar­ger than the lower because they are more com­plic­ated. They are more com­plic­ated because they are lar­ger. Just the same is true of plants.

As is typ­ic­al of Haldane, he fin­ishes with some­thing a bit more polit­ic­al than ana­tom­ic­al, stat­ing that “just as there is a best size for every anim­al, so the same is true for every human insti­tu­tion”. Some­thing to con­sider.

The devel­op­ment of the human brain is intric­ately linked with almost every moment of our evol­u­tion from sea-dwell­ing anim­als to advanced, social prim­ates. That is the the over­whelm­ing theme from New Sci­ent­ist’sÂ brief his­tory of the brain.

The enga­ging art­icle ends with a look at the con­tin­ued evol­u­tion of the human brain (“the visu­al cor­tex has grown lar­ger in people who migrated from Africa to north­ern lat­it­udes, per­haps to help make up for the dim­mer light”), and this on why our brains have stopped grow­ing:

So why didn’t our brains get ever big­ger? It may be because we reached a point at which the advant­ages of big­ger brains star­ted to be out­weighed by the dangers of giv­ing birth to chil­dren with big heads. Or it might have been a case of dimin­ish­ing returns.

Our brains are pretty hungry, burn­ing 20 per cent of our food at a rate of about 15 watts, and any fur­ther improve­ments would be increas­ingly demand­ing. [â€¦]

One way to speed up our brain, for instance, would be to evolve neur­ons that can fire more times per second. But to sup­port a 10-fold increase in the “clock speed” of our neur­ons, our brain would need to burn energy at the same rate as Usain Bolt’s legs dur­ing a 100-metre sprint. The 10,000-calorie-a-day diet of Olympic swim­mer Michael Phelps would pale in com­par­is­on.

Not only did the growth in the size of our brains cease around 200,000 years ago, in the past 10,000 to 15,000 years the aver­age size of the human brain com­pared with our body has shrunk by 3 or 4 per cent. Some see this as no cause for con­cern. Size, after all, isn’t everything, and it’s per­fectly pos­sible that the brain has simply evolved to make bet­ter use of less grey and white mat­ter. That would seem to fit with some genet­ic stud­ies, which sug­gest that our brain’s wir­ing is more effi­cient now than it was in the past.

Oth­ers, how­ever, think this shrink­age is a sign of a slight decline in our gen­er­al men­tal abil­it­ies.

The longest con­tinu­ous evol­u­tion exper­i­ment was star­tedÂ in 1988 and is still ongo­ing. The study, examin­ing the “evolvab­il­ity” of Escheri­chia coli (E. coli), has recently sur­passed 52,000 gen­er­a­tions and has had a sample of the pop­u­la­tion frozen and savedÂ every 75 days (every 500 gen­er­a­tions). The wealth of data obtained is fant­ast­ic and these frozen ancest­or­sÂ have beenÂ the focus ofÂ a recent study that set out to find wheth­er the even­tu­al “evol­u­tion­ary win­ners” dis­played signs of their genet­ic superi­or­ity hun­dreds of gen­er­a­tions earli­er.

“[The idea of] selec­tionÂ for evolvab­il­ity has been in the air for a long time, but this is one of the first real sys­tem­at­ic and expli­cit demon­stra­tions of this actu­ally hap­pen­ing,” said evol­u­tion­ary bio­lo­gist and pop­u­la­tion genet­i­cist Michael Desai of Har­vard Uni­ver­sity [â€¦]

The first sur­prise came when the team com­pared the fit­ness of four strains – two EWsÂ [even­tu­al win­ners] and two ELs [even­tu­al losers] – and found that while all four strains had sig­ni­fic­antlyÂ high­er fit­ness than the ances­tral strain, the ELs appeared more fit than the EWs. Com­par­ing the four strains dir­ectly con­firmed the res­ult: The two EW strains were at a sig­ni­fic­ant dis­ad­vant­age to the ELs. If these strains had not accu­mu­lated any more muta­tions, the research­ers estim­ated the EWsÂ would have gone extinct in just 350 addi­tion­al gen­er­a­tions. [â€¦]

The res­ults sug­ges­ted that the EWs, while ini­tially at a dis­ad­vant­age, pre­vailed in the long-term because they were more likely to acquire more bene­fi­cial muta­tions. In oth­er words, the EWsÂ had great­er evolvab­il­ity.

This seems like evol­u­tion­ary evid­ence for the premise of Tim Harford’s latest book, Adapt.